novus log

看了網路上一些錯覺圖後產生靈感，就隨手寫了個小程式來驗證想法，不過效果似乎不太好。我也不知道其他人看起來感覺如何，歡迎回饋意見讓我知道。
程式執行後會在同資料夾輸出 maze.bmp ，如下圖。 (滑鼠請點擊放大，才看得到效果)

重口味版本

因為是一邊產生一邊寫檔，所以一些圖形細節的部分就懶得處理了。
程式碼草稿如下，因為只是驗證概念，程式碼寫得比較隨性。

#include <cstdlib>
#include <cstdio>
#include <ctime>
#include <algorithm>

using namespace std;

const int W = 55, H = 37;
const int BSIZE = 16, DEPTH = 2;
const int FACE[][3] = { {210, 210, 0}, {0, 102, 255} };
const int EDGE[][3] = { {255, 255, 255}, {0, 0, 0}, {100, 128, 128} };

const int *lColor = EDGE[0], *rColor = EDGE[1];
const int *tColor = EDGE[1], *bColor = EDGE[0];
char mz[(W+1) * (H+2)] = {0};

void Gen(int p, int d) 
{
  if (mz[p] == 1) {
    int v[] = {-1, 1, -(W + 1), W + 1};
    random_shuffle(v, v + 4);
    mz[p] = mz [p - d] =  0;
    for (int i = 0; i < 4; ++i) Gen(p + 2 * v[i], v[i]);
  }
}

inline void PushWord(char*& buf, unsigned w)
{
  buf[0] = w;
  buf[1] = w >> 8;
  buf[2] = w >> 16;
  buf[3] = w >> 24;
  buf += 4;
}

char* FillRGB(char* buf, int r, int g, int b, int count  = 1)
{
  for (int i = 0; i < count; ++i) {
    buf[0] = b;
    buf[1] = g;
    buf[2] = r;
    buf += 3;
  }
  return buf;
}

void DrawSeg(char* buf, const int* c0, const int* c1, const int* c2)
{
  buf = FillRGB(buf, c0[0], c0[1], c0[2], DEPTH);
  buf = FillRGB(buf, c1[0], c1[1], c1[2], BSIZE-2*DEPTH);
  buf = FillRGB(buf, c2[0], c2[1], c2[2], DEPTH);
}

void DrawBox(char** buf, int offset, int curr, int left, int right, int top, int bot)
{
  if (curr) {
    const int *c0, *c1, *c2;
    c0 = (lColor != tColor) && !(top ^ left)? EDGE[2] : (top? lColor : tColor);
    c1 = top?  FACE[1] : tColor;
    c2 = (rColor != tColor) && !(top ^ right)? EDGE[2] : (top? rColor: tColor);
    DrawSeg(buf[0] + offset, c0, c1, c2);

    c0 = left?  FACE[1] : lColor;
    c2 = right? FACE[1] : rColor;
    DrawSeg(buf[1] + offset, c0, FACE[1], c2);

    c0 = (lColor != bColor) && !(bot ^ left)? EDGE[2] : (bot? lColor : bColor);
    c1 = bot?  FACE[1] : bColor;
    c2 = (rColor != bColor) && !(bot ^ right)? EDGE[2] : (bot? rColor: bColor);
    DrawSeg(buf[2] + offset, c0, c1, c2);
  } else {
    for (int i = 0; i < 3; ++i) 
      FillRGB(buf[i] + offset, 210, 210, 0, BSIZE);
  }
}

void WriteBMP()
{
  size_t width = (W+2) * BSIZE, height = (H+2) * BSIZE;
  size_t rowSize = width * 3;
  size_t pad = (4 - (rowSize & 0x03)) & 0x03;
  size_t dataSize = (rowSize + pad) * height;

  char header[54] = "BM";
  char* ph = header + 2;
  PushWord(ph, dataSize + 54);    
  PushWord(ph, 0);
  PushWord(ph, 54);               
  PushWord(ph, 40);
  PushWord(ph, width);            
  PushWord(ph, height);
  PushWord(ph, 0x00180001);       
  PushWord(ph, 0);
  PushWord(ph, dataSize);         
  PushWord(ph, 0);
  PushWord(ph, 0);                
  PushWord(ph, 0);
  PushWord(ph, 0);

  FILE* fout = fopen("maze.bmp", "wb");
  fwrite(header, 1, 54, fout);

  char* rowBuf[3];
  rowBuf[0] = new char[3 * (rowSize + pad)];
  rowBuf[1] = rowBuf[0] + rowSize + pad;
  rowBuf[2] = rowBuf[1] + rowSize + pad;

  for (int i = 0; i < 3; ++i)
    FillRGB(rowBuf[i], 210, 210, 0, width);
  for (int i = 0; i < BSIZE; ++i) 
    fwrite(rowBuf[0], 1, rowSize + pad, fout);

  for (int j = 0; j < H; ++j) {
    char* prev = mz + j * (W+1);
    char* curr = mz + (j+1) * (W+1);
    char* next = mz + (j+2) * (W+1);

    if (((H-1-j) % (H/4)) == (H/8)) swap(tColor, bColor);
    for (int i = 0; i < W; ++i) {
      if ((i % (W/4)) == (W/8)) swap(lColor, rColor);
      DrawBox(rowBuf, (i+1)*BSIZE*3, curr[i], 
      curr[i-1], curr[i+1], prev[i], next[i]);
    }
    for (int i = 0; i < DEPTH; ++i)
      fwrite(rowBuf[0], 1, rowSize + pad, fout);
    for (int i = 0; i < BSIZE - 2 * DEPTH; ++i)
      fwrite(rowBuf[1], 1, rowSize + pad, fout);
    for (int i = 0; i < DEPTH; ++i)
      fwrite(rowBuf[2], 1, rowSize + pad, fout);
  }
  FillRGB(rowBuf[0], 210, 210, 0, width);
  for (int i = 0; i < BSIZE; ++i) 
    fwrite(rowBuf[0], 1, rowSize + pad, fout);

  delete[] rowBuf[0];
  fclose(fout);
} 

int main()
{
  for (char* row = mz+W+1; row < mz + (H+1)*(W+1); row += W+1)
    fill(row, row + W, 1);
  srand(time(0));
  int x = (rand() % (W/2)) * 2 + 1;
  int y = (rand() % (H/2)) * 2 + 2;
  Gen((W+1)*y+x, 0);
  WriteBMP();
}